docs: def maxval_cutout_pos(self):
          """
          The ``(y, x)`` coordinate, relative to the `data_cutout`, of the
          maximum pixel value of the ``data`` within the source segment.
  
          If there are multiple occurrences of the maximum value, only the
          first occurence is returned.
          """
  
          if self._is_completely_masked:
              return (np.nan, np.nan) * u.pix
          else:
              arr = self.data_cutout_ma
              # multiplying by unit converts int to float, but keep as
              # float in case of NaNs
              return np.asarray(np.unravel_index(np.argmax(arr),
                                                 arr.shape)) * u.pix